DOCTOR WHO/TORCHWOOD SPOILERS
In addition to Billie Piper returning to Doctor Who for three episodes in series four, John Barrowman has also dropped a hint that Captain Jack will be there, as well. Given that Catherine Tate (as former runaway bride Donna Noble) will be on hand for the entire season, plus Freema Agyeman (as Martha Jones) will be returning mid-series (after appearing as Jones for three episodes on Torchwood), it would appear that David Tennant (The Doctor) will have quite a surplus of romantic possibilities on board the Tardis.
All we need now is for Noel Clarke and Elisabeth Slaydon to show up. (Peter Davison has already appeared in the short Time Crash with Tennant as part of this years Children In Need telethon.)